S-G-08—Specification for the verification, reverification, installation and use of electronic volume conversion devices and functions

Category: Gas
Issue date:
Effective date:
Revision number: N/A
Supersedes: N/A


Table of contents


Note: In order to provide organizations currently accredited by Measurement Canada (MC) for the verification and reverification of electronic volume conversion (EVC) devices or functions with sufficient time to update their quality management system documentation, the following implementation schedule applies:

1.0 Purpose

This specification establishes requirements for the verification, reverification, installation and use of EVC devices and functions approved by MC for use in trade measurement and custody transfer applications.

2.0 Scope

2.1 Types of electronic volume conversion devices and functions

This specification applies to EVC devices designed and intended for use with a single volumetric gas flow meter and to EVC functions built into volumetric gas flow meters.

These EVC devices and functions include a built-in pressure sensor and/or temperature sensor, which provide for volume conversion as a function of:

These EVC devices and functions may also include a volume to energy conversion function.

2.2 Inspection location

Inspection of an EVC device or function must be conducted at:

2.3 Exclusions

This specification does not apply to the following devices:

3.0 References

4.0 Authority

This specification is issued under the authority of section 18 of the Electricity and Gas Inspection Regulations.

5.0 Definitions

Base pressure, Pb (pression de base)
The reference value of pressure to which a volume of gas at a different pressure is converted.
Base temperature, Tb (température de base)
The reference value of temperature to which a volume of gas at a different temperature is converted.
Base volume (volume de base)
The volume of gas referenced to base pressure and base temperature.
Calorific value (pouvoir calorifique)
The amount of energy stored in a fixed unit of volume that is referenced to particular conditions of pressure and temperature (e.g. base conditions). Other terms used in legislation and the natural gas industry for this property include "calorific power", "energy density" and "heating value". For the purposes of this specification, the calorific value of a gas is its gross volumetric heating value established on a real, dry basis by measurement or calculation.
Configurable device (appareil configurable)
A device designed such that the information received from its measurement inputs can be selected and/or processed in different ways to suit different measurement applications. Includes any device approved to permit legally relevant parameters to be deleted, appended to, modified, or substituted in whole or in part directly by the authorized operator or a communications link from another device, such as a local or remote console or computer, whether or not the secondary apparatus is part of the network connecting the devices.
Configurable parameter (paramètre configurable)
Any adjustable or selectable parameter within a configurable device that can have an effect on the accuracy of a device or can significantly increase the potential for fraudulent use of the device and, based on its nature, may need to be updated on an ongoing basis, or only during device installation or upon replacement of a component.
Defect (défaut)
A departure of a meter's quality characteristic from its intended level or state that occurs with a severity sufficient to cause the meter to not satisfy normal usage requirements. Depending on its nature and severity, a defect may cause nonconformity to occur immediately or at some time in the future.
Ultrasonic domestic gas flow meter (débitmètre de gaz domestique à ultrasons)
An ultrasonic gas flow meter which includes a battery-powered register and associated processing circuitry, all enclosed within the same meter case and used to measure volumes of gas at working pressures up to a maximum of 200 kPa (or 29 lb per square inch).
Electronic volume conversion device or function (dispositif ou fonction de conversion du volume électronique)
An electronic device or an electronic function built into a volumetric gas flow meter that converts a volume of gas at a particular pressure and temperature (e.g. flowing conditions) to the volume at base pressure and/or temperature. The device or function may also apply supercompressibility correction to account for the deviation of a real gas from the ideal gas law.
Event (événement)
An action during which one or more changes are made to a legally relevant parameter. Events include software updating and event log exporting.
Event log (registre d'événements)
A compilation of event records.
Event logger (consignateur d'événements)
A secure form of audit trail containing a series of records, where each record contains a number corresponding to a specific event.
Hash code (code haché)
A code calculated based on the contents of a subject. Hash codes can be used to demonstrate that the contents of a subject have not been modified.
Legally relevant (juridiquement pertinent)
Software, hardware, data or a part thereof which interferes with properties regulated by legal metrology.
Legally relevant parameter (paramètre juridiquement pertinent)
A parameter of a measuring instrument, an electronic device or a sub-assembly subject to legal control. Legally relevant parameters typically form part of the legally relevant functions performed by a device. The following types of legally relevant parameters can be distinguished: type-specific parameters and device-specific parameters. For the purposes of this specification, legally relevant parameters are those which are, either individually or as part of a function, subject to verification under the Electricity and Gas Inspection Act.
Measurand (mesurande)
A quantity intended to be measured.
Pressure multiplier, Pm (multiplicateur de pression)
A factor applied to a volume of gas at a particular pressure (e.g. flowing pressure) to convert it to the volume at base pressure. A electronic volume conversion device or function calculates a pressure multiplier using one of the following equations:
Equation 1

Pressure multiplier = (gauge pressure × atmospheric pressure) / base pressure or Pressure multiplier = absolute pressure / base pressure

Where,

  • Pga is the average flowing gas pressure measured on the gauge pressure scale
  • Pa is the atmospheric pressure
  • Pabs is the average flowing gas pressure measured on the absolute pressure scale
  • Pb is the base pressure
Relative error (erreur relative)
The absolute error of measurement divided by the conventional true value of the measurand, and traditionally referred to as the true error. Expressed as a percentage, the relative error is calculated using the following equation:
Equation 2

Relative error = ((meter quantity − standard quantity) / standard quantity) × 100%

Where,

  • Er is the relative error of the device under test, expressed as a percentage
  • Qm is the quantity indicated by the device under test
  • Qs is the quantity indicated by the reference standard, expressed in the same units as Qm
Reverification (revérification)
A subsequent confirmation of a meter's conformance to legal requirements following the initial confirmation of its conformance to those same requirements (i.e. verification) performed upon expiration of the meter's initial verification period and each subsequent reverification period.
Span (étendue de mesure)
The maximum value of a measuring range minus its minimum value.
Supercompressibility factor, Fpv (facteur de surcompressibilité)
A factor used to correct for a deviation from the ideal gas law when converting a volume of a gas at a particular pressure and temperature (e.g. flowing conditions) to the volume at base pressure and temperature. This deviation is due to the compressibility of a real gas, which varies in composition, pressure and temperature. The supercompressibility factor is used in non-linear metering applications (e.g. differential pressure-based metering) and the supercompressibility factor squared is used in linear metering applications (e.g. non-differential pressure-based metering).
Temperature multiplier, Tm (multiplicateur de température)
A factor applied to a volume of gas at a particular temperature (e.g. flowing temperature) to convert it to the volume at base temperature. As applicable, an electronic volume conversion device or function calculates the temperature multiplier using one of the following equations:
Equation 3

Temperature multiplier = (base temperature + 459.67) / (flowing temperature + 459.67)

Equation 4

Temperature multiplier = (base temperature + 273.15) / (flowing temperature + 273.15)

Where,

  • Tga is the average flowing gas temperature
  • Tb is the base temperature
Traced update (mise à jour traçable)
The procedure of changing legally relevant or legally non-relevant software in a verified device after which the subsequent verification by a responsible party is not necessary.
Verification (vérification)
The operations carried out by an inspector or accredited organization to confirm that a meter entirely conforms to legal requirements.
Verification triggering event (événement déclencheur de vérification)
Any event deemed by Measurement Canada to require reverification of a device before it can be used or continue to be used in trade. An event logger's recording of a verification triggering event has the same ramifications and consequences as the breaking of a device's physical seal.

6.0 General

6.1 Approved range of measurement

Except where otherwise specified, any references in this specification to an EVC device or function's measuring range (including its minimum and maximum values) for pressure or temperature are to be considered as references to its approved range or a configured range within its approved range.

6.2 Conforming devices or functions

An EVC device that conforms to an approved type and to all applicable requirements of this specification is considered verified or reverified, as applicable.

A gas flow meter with a built-in EVC function must conform to an approved type and all applicable requirements of this and any other applicable specification to be considered verified or reverified, as applicable.

6.3 Nonconforming devices or functions

An EVC device or function that does not conform to all applicable requirements of this specification, or that possesses a defect that could affect its ability to satisfy normal usage requirements, is considered nonconforming and is not accepted for the purposes of verification or reverification.

6.4 Disposition of nonconforming devices

Nonconforming or defective EVC devices and functions may only be resubmitted for inspection after their deficient quality characteristics have been corrected.

6.5 Verification and reverification procedures

Inspection of EVC devices and functions for the purpose of verification or reverification is to be conducted in accordance with an inspection procedure developed by MC or authorized by MC for use by an accredited organization.

7.0 Administrative requirements

7.1 Marking requirements

7.1.1 Electronic volume conversion device

An EVC device must be marked clearly and legibly:

7.1.2 Electronic volume conversion function

A gas flow meter with a built-in EVC function must be marked clearly and legibly with all the applicable EVC-related information indicated in the markings section of the NOA and required by specification S-G-03.

7.2 Legally relevant software version

The legally relevant software parts installed in an EVC device or function must be of a version that is indicated in its NOA.

7.3 Legally relevant software hash code

If an EVC device or function is approved with a traced update capability, the generated hash code for each installed legally relevant software part must match the hash code for the corresponding software part and version indicated in the NOA.

7.4 Interrogation hardware and/or software

If the NOA of an EVC device or function indicates specific interrogation hardware and/or software versions needed to access information required for inspection purposes, these versions are to be used by the inspector or accredited organization. In addition, other interrogation hardware and/or software developed and/or recommended by the manufacturer of the EVC device or function may be used to facilitate the inspection.

7.5 Configurable devices and functions

If an EVC device or function is approved to permit certain legally relevant parameters to be reconfigured (i.e. deleted, appended to, modified or substituted) without requiring reverification, the following requirements apply:

  1. Subject to b., any such parameters that the contractor or device owner intends to reconfigure following verification and sealing are to be inspected and verified in accordance with the applicable requirements of this specification.
  2. If a legally relevant function is indicated in the device's NOA as being approved to permit the use of configurable parameters within an approved range, all discrete values of such parameters within the approved range are legally relevant and are considered inspected and verified when the function is inspected and verified.

Note: If the contractor or the device owner does not inform the inspector or accredited organization that they intend to reconfigure the legally relevant parameters after the EVC device or function is verified and sealed, they risk triggering a device reverification if they switch from a verified to an unverified legally relevant parameter.

7.6 Inspection certificate or record of inspection

The following requirements apply:

  1. Subject to b., an inspection certificate issued pursuant to section 14 of the Electricity and Gas Inspection Act for each verified or reverified EVC device or gas flow meter with a built-in EVC function must include the information prescribed in section 21 of the Electricity and Gas Inspection Regulations as well as the following additional information:
    • A version identifier for each legally relevant software part.
    • A generated hash code for each legally relevant software part (if approved with a traced update capability).
    • Legally relevant parameters that may be reconfigured without triggering a reverification of the device, except for those used by legally relevant functions of the type described in 7.5 b.
    • All test results, including those associated with any legally relevant parameters indicated by the contractor in 7.5 a.
  2. If the inspection is conducted by the device owner, the record of inspection is to include the information listed in item a.
  3. As applicable, the inspection certificate or record of inspection will serve as objective evidence of inspection for any legally relevant parameters indicated in the NOA as capable of being reconfigured without requiring reverification of the device. Such objective evidence is to be provided to MC upon request.

7.7 Reverification periods

The initial and subsequent reverification periods for EVC devices and gas flow meters with a built-in EVC function are established in bulletin G-18. EVC devices that have qualified to be granted a conditionally or unconditionally lengthened initial reverification period are indicated in bulletin G-03.

8.0 Technical requirements

8.1 General

An EVC device or function must conform in every respect to the approved type described in its NOA and be free of any:

8.2 Electronic display

An EVC device or function's electronic display must be clearly readable with no missing segments or annunciators. A full segment test is to be performed if the device or function provides for it.

8.3 Leakage

Any part of an EVC device or function that is intended to contain gas must operate without leakage at any pressure up to the manufacturer's maximum rated pressure.

8.4 Communication interface

If an EVC device or function's communication interface is approved as the sole means of accessing certain information required for type approval and/or verification purposes, it must function as intended and as approved. Such information may include the firmware version, information normally marked on a nameplate, legally relevant parameters, volume conversion multipliers and event log contents.

8.5 Event logger

If an EVC device or function is approved to permit certain legally relevant parameters to be reconfigured without requiring its reverification, the functionality of its event logger is to be confirmed by reconfiguring at least one such legally relevant parameter as indicated in the NOA.

8.6 Telemetering functions or devices

8.6.1 Built-in pulse generator

Except where otherwise authorized by MC, the following requirements apply:

8.6.2 Automatic meter reading device or function

The following requirements apply:

9.0 Metrological requirements

9.1 Calibration target

The calibration target of an EVC device or function's pressure and/or temperature measurement must be as close to the conventional true value (i.e. zero absolute error) as its adjustment will allow over the applicable measuring range.

9.2 Device or function configuration

The following requirements apply:

Note: Where applicable, an EVC device or function's event logger should log each legally relevant parameter that is reconfigured during the inspection process. The event log and the inspection certificate and/or record will serve as objective evidence of the verification of the reconfigured legally relevant parameters.

9.3 Performance testing requirements

9.3.1 Pressure and temperature standards

Performance testing of an EVC device or function is to be conducted using appropriately selected working level pressure and temperature standards that have valid calibration certificates with traceability to national standards (or as may be alternatively authorized by MC).

9.3.2 Test pressure and temperature stability

During performance testing of an EVC device or function, the applied test pressure must not vary by more than ±0.1% of the target value, and the applied test temperature must not vary by more than ±0.3 ºF (±0.2 ºC), as applicable.

9.3.3 Minimum test quantity

Accumulations of converted volume and energy must be of a sufficient quantity to ensure 0.1% resolution in the calculation of the performance test result. The minimum test quantity (Q) is to be calculated as follows:

Equation 5

Test quantity = smallest readable quantity / % resolution × 100%

Where,

9.3.4 Use of gas measurement software applications

Any software application used to calculate the conventional true values of a supercompressibility factor or calorific value must be evaluated and authorized for inspection purposes by MC’s senior gas engineer.

Any software application used for any other calculations and/or compliance assessments must be evaluated and authorized for inspection purposes by MC’s regional gas specialist or senior gas engineer.

9.3.5 Application of performance testing requirements

This specification's performance testing requirements apply to EVC devices or functions as follows:

9.3.6 Unconverted volume registration

An EVC device's mechanical and/or electronic registration of unconverted volume is to be tested in accordance with the following requirements:

  1. A single volume accumulation test is required using a rate of volumetric input that does not exceed the maximum value indicated in the NOA or specified by the manufacturer.
  2. If the device detects instrument drive revolutions or low frequency pulses:
    1. the accumulation must be of a sufficient quantity to assess the device's mechanical and/or electronic registration of unconverted volume based on the following test parameters:
      • Number of applied revolutions or pulses;
      • Volume per revolution or volume per pulse configured in the device,
      • Volume per revolution marked on the mechanical index; and/or
      • Unconverted volume multiplier configured in the device;
    2. the conventional true value of the accumulated unconverted volume (Vunconv) is to be calculated using the applicable equation:

      Equation 6

      Unconverted volume = (number of revolutions × volume per revolutions) / multiplier Or Unconverted volume = (number of low frequency pulses × volume per pulse) / multiplier

      Where,

      • # of revs is the number of actual or simulated instrument drive revolutions applied to the device
      • Volume / rev is the volume per instrument drive revolution marked and/or configured in the device
      • # of LF pulses is the number of low frequency pulses applied to the device
      • Volume / pulse is the volume per pulse configured in the device
      • Multiplier is the unconverted volume multiplier marked and/or configured in the device
  3. If the device detects high frequency pulses or a flow meter's impeller shaft revolutions (via a magnetic coupling):
    1. the accumulation test must be of a sufficient quantity to ensure 0.02% resolution in the calculation of the performance accuracy (expressed as a relative error) of its registered unconverted volume, and
    2. the conventional true value of the accumulated unconverted volume (Vunconv) is to be calculated using the applicable equation shown below:

      Equation 7

      Unconverted volume = number of high frequency pulses / (number of pulses per unit volume × multiplier) Or Unconverted volume = (number of revolutions × volume displacement) / multiplier

      Where,

      • # of HF pulses is the number of high frequency pulses applied to the device
      • K is the number of high frequency pulses per unit of volume configured in the device
      • # of revs is the number of actual or simulated impeller shaft revolutions applied to the device
      • Vdisp is the displacement volume (i.e. volume per impeller revolution) configured in the device
      • Multiplier is the unconverted volume multiplier marked and/or configured in the device

9.3.7 Pressure multiplier

The performance accuracy of an EVC device or function's pressure multiplier is to be tested in accordance with the following requirements:

  1. If the device or function's pressure multiplier is not readily accessible, its apparent pressure multiplier may be calculated and tested using the applicable pressure multiplier equation in section 5.0, and the device or function's indicated gauge or absolute pressure (as applicable), configured atmospheric pressure (as applicable) and base pressure.
  2. A performance test is required at each test point specified in Table 1.
    Table 1: Pressure test points
    Test point designation Pressure test points (percentage of span)
    P1 20 ± 2
    P2 50 ± 2
    P3 80 ± 2
  3. The test pressure for a specified test point is to be calculated as follows:

    Equation 8

    Test pressure = (test point / 100 × (maximum pressure − minimum pressure) + minimum pressure) ± (0.02 × (maximum pressure − minimum pressure))

    Where,

    • Test point is the pressure test point specified in Table 1
    • Pmax is the maximum value of the device or function's pressure measuring range
    • Pmin is minimum value of the device or function's pressure measuring range
  4. If the device or function measures absolute pressure and the calculated test pressure for the P1 test point is less than local atmospheric (i.e. barometric) pressure, the test is to be conducted at atmospheric pressure.
  5. The conventional true value of the pressure multiplier is to be calculated using:

    • the applicable equation in section 5.0,
    • the pressure indicated by a reference standard, and
    • the atmospheric pressure (as applicable) and base pressure configured in the device or function.

9.3.8 Temperature multiplier

The performance accuracy of an EVC device or function's temperature multiplier is to be tested in accordance with the following requirements:

  1. If the device or function's temperature multiplier is not readily accessible, its apparent temperature multiplier may be calculated and tested instead using the applicable equation in section 5.0, and the device or function's indicated temperature and configured base temperature.
  2. An EVC device or function that only measures temperature may have its indicated temperature tested as an alternative to its temperature multiplier or apparent temperature multiplier.
  3. Subject to d., a performance test is required at each test point specified in Table 2.
    Table 2: Temperature test points
    Test point designation Temperature test points
    T1 86 ± 4 °F (30 ± 2 °C)
    T2 59 ± 4 °F (15 ± 2 °C)
    T3 32 ± 4 °F (0 ± 2 °C)
  4. A single performance test may be conducted using a temperature between the T1 and T3 test points specified in Table 2, provided the device or function does not have a supercompressibility correction function and a maximum pressure exceeding 300 psig or psia, or the metric equivalent.
  5. An accredited organization testing EVC devices and functions in accordance with d. must identify the temperature test point they are using in their accreditation documentation (e.g. inspection procedure) and inspection certificates or records.
  6. The conventional true value of the temperature multiplier is to be calculated using:
    • the applicable equation in section 5.0,
    • the temperature indicated by a reference standard, and
    • the device or function's configured base temperature.

9.3.9 Supercompressibility correction function

The performance accuracy of an EVC device or function's supercompressibility correction function is to be tested in accordance with the following requirements:

  1. If the device or function's supercompressibility factor squared (Fpv2) is not readily accessible, the square of its supercompressibility factor (Fpv) may be tested.
  2. Subject to c., a performance test is required at each test point combination specified in Table 3.

    Table 3: Supercompressibility correction test points
    Test point combinations Pressure test points (% of span) Temperature test points
    P1 and T1 20 ± 2 86 ± 4 °F (30 ± 2 °C)
    P2 and T2 50 ± 2 59 ± 4 °F (15 ± 2 °C)
    P3 and T3 80 ± 2 32 ± 4 °F (0 ± 2 °C)
  3. A single performance test may be conducted at the P3 and T3 test point combination, provided the device or function's maximum pressure does not exceed 300 psig or psia, or the metric equivalent.
  4. The conventional true value of the supercompressibility factor squared is to be calculated using:
    • a software application authorized for use by MC,
    • the standard and method of calculation used by the device or function,
    • the pressure and temperature indicated by reference standards, and
    • the device or function's configured gas composition, relative density (as applicable), base pressure and base temperature.

9.3.10 Volume conversion function

The performance accuracy of an EVC device or function's volume conversion function is to be tested in accordance with the following requirements:

  1. Subject to b., a single volume accumulation is required for test number one as specified for the applicable conversion type in Table 4, or as specified in Table 5 if the testing in 9.3.8 is conducted using a single temperature only.
  2. If the device or function's pressure multiplier or pressure, temperature multiplier or temperature, and supercompressibility factor squared or supercompressibility factor are not accessible (subject to the conversion type), a volume accumulation is required for each test number specified for the applicable conversion type in Table 4, or alternatively specified in Table 5 for single temperature testing.
    Table 4: Volume conversion test points and maximum permissible errors
    Conversion type Test no. Test point combinations Pressure test points (% of span) Temperature test points Maximum permissible error
    Pressure only
    • 1
    • 2
    • 3
    • P3
    • P2
    • P1
    • 80 ± 2
    • 50 ± 2
    • 20 ± 2
    N/A ± 1.0 %
    Temperature only
    (with or without fixed Pm)
    • 1
    • 2
    • 3
    • T3
    • T2
    • T1
    N/A
    • 32 ± 4 °F (0 ± 2 °C)
    • 59 ± 4 °F (15 ± 2 °C)
    • 86 ± 4 °F (30 ± 2 °C)
    ± 1.0 %
    Pressure and temperature only
    • 1
    • 2
    • 3
    • 4
    • 5
    • P3 and T3
    • P2 and T2
    • P1 and T1
    • P3 and T1
    • P1 and T3
    • 80 ± 2
    • 50 ± 2
    • 20 ± 2
    • 80 ± 2
    • 20 ± 2
    • 32 ± 4 °F (0 ± 2 °C)
    • 59 ± 4 °F (15 ± 2 °C)
    • 86 ± 4 °F (30 ± 2 °C)
    • 86 ± 4 °F (30 ± 2 °C)
    • 32 ± 4 °F (0 ± 2 °C)
    ± 1.4 %
    Pressure, temperature and supercompressibility
    • 1
    • 2
    • 3
    • 4
    • 5
    Same as above Same as above Same as above ±1.5%
    Table 5: Alternate volume conversion test points and maximum permissible errors
    Conversion type Test no. Test point combinations Pressure test points (% of span) Temperature test point Maximum permissible error
    Temperature only (with or without fixed Pm) 1 T N/A Single point within
    T1 and T3 test points specified in Table 4
    ±0.5%
    Pressure and temperature only
    • 1
    • 2
    • 3
    • P3 and T
    • P2 and T
    • P1 and T
    • 80 ± 2
    • 50 ± 2
    • 20 ± 2
    Single point within
    T1 and T3 test points specified in Table 4
    ±1.1%
    Pressure, temperature and supercompressibility
    (if Pmax ≤ 300 psi)*
    • 1
    • 2
    • 3
    • P3 and T3
    • P2 and T3
    • P1 and T3
    • 80 ± 2
    • 50 ± 2
    • 20 ± 2
    32 ± 4 °F (0 ± 2 °C) ± 1.1 %

    * Single temperature testing doesn't apply to EVC devices or functions having supercompressibility correction and a maximum pressure exceeding 300 psig or psia, or the metric equivalent.

  3. The rate of volumetric input applied to the device or function must not exceed the maximum value indicated in the NOA or specified by the manufacturer.
  4. The conventional true value of an accumulated converted volume (Vconv) is to be calculated using the applicable equation in Table 6.

    Table 6: Calculation of conventional true value of converted volume
    Conversion type Converted volume equation
    Pressure only
    Equation 9

    Converted volume = unconverted volume × pressure multiplier

    Temperature only
    Equation 10

    Converted volume = unconverted volume × temperature multiplier

    Temperature only with fixed pressure multiplier
    Equation 11

    Converted volume = unconverted volume × temperature multiplier × fixed pressure multiplier

    Pressure and temperature only
    Equation 12

    Converted volume = unconverted volume × pressure multiplier × temperature multiplier

    Pressure, temperature and supercompressibility
    Equation 13

    Converted volume = unconverted volume × pressure multiplier × temperature multiplier × supercompressibility factor squared

    Where,

    • Vunconv is the accumulated unconverted volume indicated by the device or function
    • Pm is the conventional true value of the pressure multiplier, calculated as specified in 9.3.7 e.
    • Tm is the conventional true value of the temperature multiplier, calculated as specified in 9.3.8 f.
    • Pm(f) is the fixed pressure multiplier configured in the device or function
    • Fpv2 is the conventional true value of the supercompressibility factor squared, calculated as specified in 9.3.9 d.

9.3.11 Volume to energy conversion

The performance accuracy of an EVC device or function's unconverted volume to energy conversion function is equivalent to the overall performance accuracy of its volume conversion function and base volume to energy conversion function combined. This performance accuracy is to be tested in accordance with the following requirements:

  1. A single energy accumulation is required using the pressure and temperature test point combination that was used for test number one of the volume conversion function in 9.3.10.
  2. As applicable, the conventional true value of the calorific value is:
    • the fixed value configured in the device or function, or
    • to be calculated using a software application authorized for use by MC, the device or function's configured standard and method of calculation of calorific value, gas composition parameters, base pressure, base temperature and units of measure.
  3. The conventional true value of the accumulated energy (E) is to be calculated as follows:

    Equation 14

    Energy = converted volume × calorific value × conversion factor

    Where,

    • Vconv is the accumulated base (i.e. converted) volume indicated by the device or function
    • CV is the conventional true value of the calorific value
    • CF is the conversion factor used to account for any difference between the device or function's base conditions for its converted volume and the volumetric component of its fixed or calculated calorific value

9.4 Maximum permissible errors

9.4.1 Unconverted volume registration

If the device detects:

9.4.2 Pressure multiplier

The performance accuracy (expressed as a relative error) of an EVC device or function's pressure multiplier or apparent pressure multiplier (as applicable) must not exceed an MPE of ±1.0%.

9.4.3 Temperature multiplier

The following performance requirements apply:

  1. Subject to b., the performance accuracy (expressed as a relative error) of an EVC device or function's temperature multiplier or apparent temperature multiplier must not exceed an MPE of:
    • ±1.0% when tested at three temperatures, or
    • ±0.5% when tested at a single temperature.
  2. If the indicated temperature of an EVC device or function that only measures temperature is tested, the device or function's performance accuracy (expressed as an absolute error) must not exceed an MPE of:
    • ±5.0 °F (±2.8 °C) when tested at three temperatures, or
    • ±2.5 °F (±1.4 °C) when tested at a single temperature.

9.4.4 Supercompressibility correction function

The performance accuracy (expressed as a relative error) of an EVC device or function's supercompressibility factor squared (Fpv2) or the square of its supercompressibility factor (Fpv) must not exceed an MPE of:

9.4.5 Volume conversion function

The following performance requirements apply:

  1. The performance accuracy (expressed as a relative error) of an EVC device or function's volume conversion function must not exceed the MPE specified for the conversion type tested in accordance with Table 4 or 5, whichever was used for performance testing.
  2. For EVC devices or functions that measure pressure and temperature but do not apply supercompressibility correction, the sum of the test result of any pressure multiplier (or apparent pressure multiplier) and of any temperature multiplier (or apparent temperature multiplier) must not exceed an MPE of:
    • ±1.4% if tested using three temperatures, or
    • ±1.1% if tested using a single temperature.

9.4.6 Volume to energy conversion function

The following performance requirements apply:

  1. If an EVC device or function is configured to apply a fixed calorific value, no error is permitted in its base (i.e. converted) volume to energy conversion function.
  2. b. If an EVC device of function is configured to calculate a calorific value, the performance accuracy (expressed as a relative error) of its base volume to energy conversion function must not exceed an MPE of ±0.10%.
  3. Note: An EVC device or function's base volume to energy conversion function is a calculator function that is assessed during type approval evaluation. Therefore, any nonconforming performance may be due to a configuration error, an incorrect interpretation of its configuration, or a combination of both. The inspector or accredited organization should confirm the validity of the performance test result before concluding on its conformity.

  4. The performance accuracy (expressed as a relative error) of the device or function's unconverted volume to energy conversion:
    • is the sum of any test result established for the volume conversion function in 9.3.10 and the test result (expressed as a relative error) established for the base volume to energy conversion function in 9.3.11, and
    • must not exceed the MPE applied to the volume conversion function test results established in 9.3.10.

10.0 Acceptance sampling inspection requirements

For future use.

11.0 Compliance sampling inspection requirements

For future use.

12.0 Sealing requirements

Except where otherwise authorized by MC, a verified or reverified EVC device, or gas flow meter with a built-in EVC function, is to be sealed and secured in accordance with the provisions of its NOA and the requirements of provisional specification PS-EG-02. Where an EVC device and a gas flow meter are inspected and verified as a single device, a verification seal is required to secure them to each other.

13.0 Installation requirements

A verified or reverified EVC device, or gas flow meter with a built-in EVC function, is subject to the following installation requirements:

14.0 Use requirements

A verified or reverified EVC device, or an EVC function built into a verified or reverified gas flow meter, is subject to the following use requirements:

  1. The device must be used with an approved and compatible gas flow meter.
  2. The device or function must be used within its approved ranges for:
    • ambient temperature,
    • flowing gas pressure (as applicable),
    • flowing gas temperature (as applicable),
    • rate of volumetric input (or as otherwise specified by the manufacturer if not indicated in its NOA).
  3. Subject to d., the device's marked and/or configured volumetric input parameter (e.g. volume per revolution or volume per pulse) must match the marked volumetric output parameter of the gas flow meter it is used with.
  4. If the device is configured with the equivalent metric value of the associated flow meter's volumetric output parameter (e.g. K factor), no error is permitted in the metric conversion calculation.
  5. The number of digits and multipliers configured in the EVC device or function for its indication of volume and/or energy must be sufficient to ensure the indicated readings are not repeated within a ninety-day period.
  6. If the device is used with a flow meter's temperature converted volumetric output (e.g. rotary meter with a temperature converting instrument drive), it must either be a non-temperature converting device or have its temperature multiplier configured with a fixed value of one. The contractor must ensure temperature conversion is not inadvertently applied twice (i.e. by the source meter and the EVC device) when using an EVC device in such an application.
  7. Except where otherwise authorized by MC, reconfiguration of an in-service device's legally relevant parameters is only permissible if the following conditions are satisfied:
    • The device is approved to permit legally relevant parameters to be deleted, appended to, modified or substituted, in whole or in part, directly by an authorized entity (locally or remotely) without requiring device reverification (in accordance with specifications S-EG-05 and S-EG-06).
    • Any legally relevant parameter to be modified is indicated in the device or function's NOA as being capable of being reconfigured without requiring a reverification of the device.
    • The reconfiguration involves switching from one previously verified legally relevant parameter to another.
    • The reconfiguration is performed by a party that is authorized by the contractor.
  8. Upon request by MC, and as applicable, the contractor is required to provide access to the contents of a device or function's event logger and objective evidence of its previous inspection (i.e. inspection certificate or record).
  9. Subject to g., if the device or function is used in a pressure factor metering installation, it may be configured with a fixed pressure multiplier value (i.e. contract value) if this capability is indicated in its NOA as being approved for such use. The contractor must ensure the pressure multiplier is not inadvertently applied twice (i.e. by the EVC device and the billing department) in such an application.
  10. Subject to g., and as applicable, the device must be used with configured gas composition and/or gas property values (e.g. specific gravity / relative density or calorific value) that are traceable to an approved gas analysis device and are representative of the flowing gas being metered. Upon request by MC, the contractor is required to provide objective evidence of the traceability of configured gas parameters and of their being representative of the flowing gas being metered.
  11. Any modification of the device's volume and/or energy values is deemed a verification triggering event.
  12. Any adjustment, modification or exchange made to the device or function's calibration and/or hardware components is deemed a verification triggering event.
  13. Reconfiguration of the device or function's legally non-relevant parameters and legally non-relevant functions is permissible, provided it has no impact on the device's legally relevant functions, performance or verification status (e.g. breaking a verification seal).
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